>Date: Thu, 22 Feb 96 11:00:46 +0100
>From: Simon.MATTHEWS/OU=ag/OU=agrate1/OU=italy@sgpgtw.sgp.st.com
>Subject: Advice needed: blowing oil
>
> The engine on my '74 MGB appears to be pressurising the crankcase and
> rocker -- some oil oil is being blown out -- however only a small
> amount: my garage floor is certainly not covered with oil, and it
> probably does not use more than a pint every 2000 miles.
>Etc.
The motorhead guys are once again right on. My '74 was doing this and I took
it as a sign of needing a ring job. I had oil spurting out of the dipstick.
I couldn't afford to do it right away, so I ventilated the filler cap with a
small drill, twice. This seemed to do the job for the time.
> What are the possible causes -- could this just be a blocked crankcase
> breather -- in which case, does anyone know how it should be plumbed?
> Car is US spec MGB, MY '74 with HIF carbs. Used to have air pump and
> gulp valve (removed by PO).
>
I have a theory that the sonabeech told me how to do the reroute plumbing
when I removed my air pump told me wrong. I had the hose coming off of the
crankcase breather and into the line to the adsorption canister. I believe
now that the way to do it is to run the crankcase line into the carbs where
the air can get recirculated. I could be wrong there, but I've seen several
other cars done like that and it makes much more sense than taking it to the
canister. There is normally some pressure in the crankcase, but too much is
a pretty good sign of piston blowby. A compression check won't catch this.
Pressurize each cylinder and see where the air comes out. This will tell you
where the problem is and what cylinder is the bad boy.
Boy, I miss that car.
Glenn
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The universe is inherently funny.
Glenn Schnittke Recovering Musician
Nashville TN 615-385-2800
glenns@edge.ercnet.com 72147.3635@compuserve.com
'74 MGB - fatally wounded
'69 MGB - prim little touring car
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